Method and apparatus for control ling the consistency of paper stock



May 20,1941.

' E. cowLEs METHOD AND APPARATUS FOR CONTROLLING THE CONSISTENCY OF PAPER STOCK Fi ld April 2, 1937 2 Sheets-Sheet M m w w.

E. COWLES May 20, 1941.

METHOD AND APPARATUS FOR CONTROLLING THE CONSISTENCY OF PAPER STOCK 2 Sheets-Shed 2 Filed April 2, 1937 *6 ORN YS.

Patented May 20, 1941 i UNITED STATE PATENT OFFICE METHOD AND APPARATUS FOR (Z'ONClROi A SISTENCY OF PAPER LING THE CON STOCK Edwin Cowles, Hopewell, N. J.-,.assignor to The Cowles Company, Princeton, N. J a corpora- 'tion of New J ersey Application April 2, 1937, Serial No. 134,412

5 Claims.

tain this control; for while regulatory devices are available for controlling high consistency stock (2% and above) with reasonable accuracy, no such device has been available for controlling low consistency stock. It is an object of the present invention to provide a method and apparatus for controlling paper stock consistencies the machine operators is relied upon'to mainwhich shall be accurate and dependable for con-- trolling both high and low consistencies, and even those extremely low consistencies (56% to 4%) which are now jrequently supplied to Fourdrinier or cylinder machines.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure l is a plan view of the apparatus.

Figure 2 is a section through the control unit.

Figure 3 is a section on the line t8 of Figure 2.

According to the present invention, it is proposedtc withdraw from the flowing stream of stock of which it is desired to control the consistency, a smaller continuously flowing stream. The withdrawn stock is agitated by an impeller,

and it will be understood that the work required to agitate the stock will vary in proportion to the consistency of the stock. That is, if the consistency of the stock increases, the work required also increases, and if the consistency decreases, the work required also decreases. Preferably the withdrawn. stock may be thickened as it is agitated thus magnifying the frictional eiiect.

Thus it will be apparent that if the quantity of water added to the flowing stream be controlled in' accordance with the amount of work required, or any suitable jindicator thereof, the consistency of the stock may be controlled. That is, if the work required tends to increase, the

pipe 2, therate of flow from pipe 2 to conduit I being controlledby valve 3.

Connected to the conduit i is a smaller conduit 4, forming the inlet conduit to the impeller unit 5. This unit comprises cover members G and I, spaced apart by an annular ring 8 thus forming an impeller chamber 9 within which the impeller l0 rotates. The impeller is driven by motor H, preferably of the constant speed type, through shaft i2. v

Formed in the cover I is an annular cham ber l8 which i's-connected to theconduit l by conduit It. This chamber is separated from the impeller chamber 9 by a screen i5'having very fine perforations i6 therein. By very fine perforations Imean perforations of a size to sub-' stantially prevent the passage of fibers therethrough. Such perforations should be of theorder-of 1 5" or less in diameter.

The agitationof the contents of the impellerchamber by rotation of the impeller may be sufficient to prevent the screen perforations from clogging with fibers, but if desired the impeller vanes may be provided with scrapers ll which engage the screen and positively clear the perioraticns of fibers.

It will be understood that the passage of water through the screen perforations has the efiect of thickening the stock in the impeller chamber, thus magnifying the frictional efiect of the agitation. The efiect may. also be increased by the provision of fins it projecting inwardly'from the wall 'of the impeller chamber.

Means are also provided for withdrawing thickened stock from the impeller chamber in order that there may be a continuous fiow of both water and fibers therethrough, said means comprising the orifice 2G communicating with conduit it connected to conduit i. v

The conduits i, it and M are provided with valves 22, 23 and 26 respectively through which the flow through the respective conduits may be adjusted in order to provide the desired conditions in the impeller chamber. It will be understood, however, that these valves are set at the beginning of the operation and are not changed during the operation, unless it is desired to alter the operating conditions. Primary control is efiected through valve 23, however, which controls the flow of water through the screen and thus controls the consistency of the stock being agitated. 1

Automatic means are provided for controlling the valve 3 in accordance with variations in the work required to agitate the contents of the impeller chamber, and such means are preterably electrical. The valve shaft 26 is provided with a gear 21 which meshes with gear 28 operated by reversible motor 29. When the motor is caused to operate in one direction the valve tends to open and when the motor is caused to operate in the reverse direction the valve tends to close.

Current for the motor II is supplied through leads 30 connected to a contacting wattmeter 3| and thence through leads 32 to the. motor. The operation of motor 29 is controlled by the wattmeter 3| in accordance with practice well known in the art. Thusthe contactor oi the wattmeter has a normal non-contacting position when themotor Ii is running at normal load. If the load increases the contactor makes a contact which starts the motor 29 in a direction to open valve 3. This increases the flow of water to conduit l which gradually reduces the load on motor ll. When it becomes normal the contact is broken and motor'29 is stopped. If the load decreases a different contact is made to drive the motor in the opposite direction to close the valve 3. Such contacting wattmeters are standard equipment 'and will not be described in detail herein.

If desired, a magnetic switch 33 of standard construction may be included between the wattmeter 3! and the motor 29 in the manner illustrated, in which case the movement the wattrate from said stock to thicken the same to a degree proportionate to the thickness of the flowing stock, continuously agitating saidthickened stock, continuously adding water to said flowing stream, and controlling the rate at which said water is added in accordance with the increase or decrease of work required to agitate said thickened stock.

3. Apparatus for controlling the consistency:

of a flowing tream 01' paper stock which comprises means or withdrawinga portion of said stream, means for agitating said withdrawn stock, means for thickening said withdrawn stock to a degree proportionate to the thickness of the flowing stock. means ior registering variations in the powerrequired to agitate said thickened stock, and means controlled by said last named meter contactor in one direction or another causes movementoi the switch in one direction or another to control the operation of the motor 29.

Itwill be understood that the invention may be variously modified and embodied within the scope of the subjoined claims. a

I claim as my invention:

1. Method of controlling the'consistencyof a continuously withdrawing water at a constant means for increasing or decreasing. the flow of water tosaid flowing stream in accordance with the increase or decrease in said power requirement.

4. Apparatus for controlling the consistency of a flowing stream of paper stock which comprises means for withdrawing continuously from said flowing stream a smaller stream of stock, means for withdrawing water continuously from said withdrawn stock .to thicken the same to a degree proportionate to the thickness of the flow-- ing stock, means for agitating continuously said thickened stock, means for registering variations in the power required to agitate said thickened stock, and means controlled by said last ,named means for increasing or decreasing the flow of water to said flowing stream in accordance with the increase or decrease in said power requirement.

5. Apparatus for controlling theconsistency of a flowing stream of paper stock which comprises means for withdrawing continuously irom said flowing stream a smaller stream or stock.

means for agitating continuously'said withdrawn stream, means for thickening said withdrawn stock to a degree proportionate to the thickness of the flowing stock, means for registering variations in the power required to agitate said thickened stock, and means controlled by said last named means for increasing or decreasing the flow of water to said flowing stream in accordance with the increase or decrease in said power requirement.

EDWIN COWLES. 

